The present invention is generally related to three-dimensional imaging, and, more particularly, the present invention is directed to computerized techniques and processor for stereoscopically and seamlessly imaging on a generally cylindrical screen.
To project stereoscopic moving images, e.g., a movie, on a planar screen, it is known to use a parallax model to account for the change in the apparent relative orientation of objects when viewed from different positions. Unfortunately, known parallax models for projecting a stereo image on a planar screen do not work well for projecting moving images on a cylindrical screen. As used herein, stereo imaging refers to images that when processed by the brain of an observer create the illusion of rendering three-dimensional (3-D) objects.
In a basic parallax model, two cameras, slightly separated apart, are used to mimic each eye of a person, and generate two slightly different pictures for the left and right picture channels to be projected on the screen. See FIG. 1 for a representation of a typical parallax model 10 for projecting 3-D images on a planar screen 11. The line connecting the respective viewpoints of each camera, such as the left and right view points 12 and 14, is called a reference line 16, which is set generally horizontal and perpendicular relative to a view axis 18 that bisects the screen 11 relative to left and right view axes 20 and 22. In parallax model 10, the reference line is spatially fixed in the same direction relative to the view axis for each picture channel.
To project moving images on a cylindrical screen, it would be desirable to subdivide the complete screen into an appropriate number of sub-screens seamlessly joined, and then one could use the same number of projectors as the number of sub-screens to project such images on the cylindrical screen. As suggested above, known parallax models generally introduce undesirable distortion to the image when a plurality of sub-screens is used because each sub-screen would need a different direction for its respective reference line, in lieu of the fixed reference line provided by known planar parallax models. This results in image discontinuity between any two adjacent sub-screens, and that is why typical parallax models that use a fixed direction for the reference line would fail to render an aesthetically-pleasing image on a cylindrical screen.
In view of the foregoing discussion, it would be desirable to provide system and techniques for projecting 3-D moving images on a cylindrical screen free from distortion and discontinuities. For example, it would be desirable to subdivide the cylindrical screen into a plurality of sub-screens combinable to generate an image aesthetically pleasing to the observer. It would be further desirable to provide continuity of the image at each juncture of any two adjacent sub-screens. It would also be desirable to provide system and techniques that provide a cost-effective solution for playing stereo movies free of optical distortion on seamlessly connected cylindrical sub-screens comprising angles of up to 360 degrees.
Generally, the present invention fulfills the foregoing needs by providing in one aspect thereof, a computerized method for stereoscopically and seamlessly imaging on a generally cylindrical screen. The method configures imaging data for a plurality of selectable sub-screens encompassing the cylindrical screen. Each sub-screen includes a plurality of selectable strips axially extending relative to a corresponding sub-screen in the cylindrical screen. The method further renders two channels of imaging data increments for each strip based on a parallax model with a reference line selectively rotatable to be in parallel alignment relative to each respective plane defined by each strip. The method combines each imaging data increment corresponding to each strip in a respective sub-screen to generate stereoscopic imaging data for that respective sub-screen, and further combines each sub-screen imaging data to generate stereoscopic imaging data substantially encompassing the angular span of the cylindrical screen.
The present invention further fulfils the foregoing needs by providing in another aspect thereof a computer-readable medium including instructions for causing a computer to process stereoscopic seamless imaging data for a cylindrical screen by:
arranging a cylindrical screen into N sub-screens, each sub-screen comprising M planar strips axially extending along a corresponding sub-screen;
rendering M increments of imaging data for each imaging channel, each increment of imaging data uniquely corresponding to a respective strip on each sub-screen; and
combining each of the M increments of imaging data for each of the N sub-screens to seamlessly form cylindrical imaging data to be projected on the cylindrical screen, wherein M and N represent respective positive integer numbers.
In yet another aspect of the present invention, a stereoscopic cylindrical screen imaging method comprising the following actions is provided:
a) gathering an externally-derived three-dimensional scene model;
b) selecting a plurality of processing parameters selected from the group consisting of angular span of the cylindrical screen, a number of sub-screens for the cylindrical screen, and a number of axially-extending planar strips for each sub-screen;
c) providing a pair of computer-synthesized cameras at the respective end points of a reference line, with each camera providing a respective view of the three-dimensional model for each imaging channel;
d) positioning the mid-point of the reference line to substantially correspond with the center of the cylinder;
e) aligning the reference line to be generally parallel relative to the plane defined by a first strip of the sub-screen;
f) generating a stereoscopic increment of imaging data for the first strip of the sub-screen;
g) rotating the reference line together with the camera pair about the center of the cylinder to be in general parallel alignment relative to the plane defined by the next strip of the sub-screen;
h) generating a stereoscopic increment of imaging data for said next strip of the sub-screen;
i) iteratively continuing with steps g) and h) until imaging data has been rendered for each strip in each of the sub-screens;
j) combining each incremental imaging data to seamlessly form cylindrical imaging data for the complete cylindrical screen; and
k) storing each sub-screen imaging data for additional processing.
In still another aspect of the present invention, a processor for stereoscopically and seamlessly imaging on a generally cylindrical screen is provided. The processor includes a module for configuring imaging data for a plurality of selectable sub-screens encompassing the cylindrical screen. Each sub-screen is made-up of a plurality of selectable strips axially extending (e.g., in a vertical direction) relative to a corresponding sub-screen in the cylindrical screen. A rendering-module is provided for rendering two channels of imaging data increments for each strip based on a parallax model with a reference line selectively rotatable to be in parallel alignment relative to each respective plane defined by each strip. A combining-module is configured to combine each imaging data increment corresponding to each strip in a respective sub-screen to generate stereoscopic imaging data for that respective sub-screen. The combining module is further configured to combine each sub-screen imaging data to generate stereoscopic imaging data substantially encompassing the angular span of the cylindrical screen.